If $a + b = -9$ and $x + y = 4$, what is $4x + 4y + 2a + 2b$ ?
Solution: $= 2a + 2b + 4x + 4y$ $= (2) \cdot (a + b) + (4) \cdot (x + y)$ $= (2) \cdot (-9) + (4) \cdot (4)$ $= -18 + 16$ $= -2$